Putin is trying to take back and reform the "old Russia" ... the one that existed before all the areas he's trying to get back had enough of Russia's rule and broke away to have a better way of living. That's the sole reason that NATO was created, to form an allegiance by the close counties to the west of Russia to form a stronger deterrent from future Russian aggression. This video does a good job of explaining some past history.
The Cuban missile crisis isn't really that analogous to what Russia is doing in Ukraine. Russia's goal during the Cuba missile crisis wasn't to "invade and take over" the USA because the USA use to be part of Russia. It was basically a deterrent by Russia during the cold war to help "protect" Cuba and give Russia an advantage to retaliate quicker if the USA ever attacked Russia or Cuba.
Thing is, Putin knows that NATO isn't going to attack Russia, so his invasion into Ukraine isn't really because he feels like NATO is going to attack him - if he actually thinks that then he's delusional and paranoid, which are the base ingredients to make for a true mad-man. NATO would never be an attacker of any country, only a defender against an attack. Putin is invading the Ukraine and any other bordering countries who are not part of NATO because he knows if they ever do join NATO that he will never be able to do a take-over with military force. He's doing it now because he's old, and he thinks this is the only opportunity for him to try and carry out a take-over that he's been thinking about for years, so he's acting it out now. And he has nukes, which he's using as a threat to try and get his way.
During the Cuban Missile Crisis, leaders of the U.S. and the Soviet Union engaged in a tense, 13-day political and military standoff in October 1962 over the
www.history.com